Context is in the annotation of contextual boundness understood in a very broad sense.
Context comprises not only immediate textual context ( "co-text "), but also wider contextual layers, including all shared or commonly known information, whose sharing may be conditioned by the situation, perception, culture, other texts, or other factors.
textual context (information deducible from the preceding text),
thought context (all shared or commonly known information),
situational context (information deducible from the situation),
sensory context (information deducible from the sensory perception),
cultural context (information shared through the culture),
intertextuality (information deducible from other related texts).
Textual context is understood dynamically, as a semantic field evolving with the course of the text. Not only does every sentence modify the whole preceding context, but the relevance of individual components of the context changes with their distance from the current sentence.
The incorporation of an expression into the context conceived in this way can take several forms - from repetition or coreference, through entailment from a larger text segment or situation, to complex meaning relationships such as e.g. a metaphor.